Biomedical Sciences ETDs

Ye Zhou

Publication Date

7-1-2011

Abstract

c-myb encodes a transcription factor that is essential for hematopoiesis and for normal development of other tissues. There is ample evidence showing the activated alleles of c-myb gene can induce leukemias in several animal species. However, there was no clear evidence showing that c-myb could be oncogenic in human cancers until recent studies revealed that the human c-myb locus is subjected to chromosomal rearrangement in some pediatric T-ALL and adenoid cystic carcinoma (ACC) patient samples. The c-myb gene contains 15 constant exons and 6 alternative exons and can undergo extensive alternative splicing. These alternatively spliced variants encode variant Myb proteins sharing the same DNA binding domain but distinct C-terminal domains. Evidence suggests that despite their identical DNA binding domains, these c-Myb variant proteins have unique transcriptional activities: the differences in the proteins allow the proteins to regulate different sets of target genes. Most importantly, some of the variants have C-terminal deletions that resemble the deletions in v-Myb, the oncogenic variant of c-Myb that can induce acute leukemias in chickens and mice. Previous studies showed that c-myb alternative splicing is tightly regulated during hematopoiesis. The profiles of c-myb alternative splicing in some leukemias are different from the profiles in normal bone marrow samples. We hypothesized that c-myb is a unique oncogene that is activated by alternative splicing in leukemias, resulting in the production of variant forms of c-Myb protein that contribute to hematopoietic cell transformation and the development of leukemia. To evaluate the clinical significance of c-myb alternative splicing and find out its correlation with leukemia, profiling of c-myb alternative splicing in a cohort of leukemia patient samples is needed. We developed a single-molecule exontyping method to characterize the alternative splicing of c-myb RNAs in a small cohort of pediatric pre-B-ALL samples and correlated the level or the pattern of c-myb splice variants with survival time of these patients. We detected that c-myb alternative splicing is more complex and more prevalent in leukemia patients than in normal cells. Furthermore, some splice variants encoding Myb proteins with truncations in the C-terminal domain are correlated with poor survival. We further explored the possibility of adapting high-throughput low-cost Next-Generation Sequencing methods to analyze c-myb alternative splicing at a large scale. We conclude that de-regulated c-myb alternative splicing could be an important contributor to the development of leukemia and that the analysis of c-myb splicing could provide a unique and novel approach of classifying leukemias, which is distinct from analyses performed with other technologies, such as microarray assays of gene expression.

Keywords

c-myb, alternative splicing, biomarker, next-generation sequencing, single molecule assay

Sponsors

NIH

Document Type

Dissertation

Language

English

Degree Name

Biomedical Sciences

Level of Degree

Doctoral

Department Name

Biomedical Sciences Graduate Program

First Committee Member (Chair)

Ozben, Michelle

Second Committee Member

Hathaway, Helen

Third Committee Member

Edwards, Jeremy

Fourth Committee Member

Ness, Scott

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